1. Field of the Invention
The present invention relates to adjustable clamping mechanisms and, more particularly, to an adjustable clamping apparatus especially suited for securing and maneuvering both rectangular as well as circular and noncircular cross-sectional tubing.
2. Description of Related Art
Clamping mechanisms used for securing and maneuvering work pieces during machining operations are well known in the art, and the field is plentiful with various methods for clamping various shaped workpieces. Basic V-block supports are among the most common types of supports due to their ability to secure both circular and rectangular cross-sectional work pieces (see, for example, Lawrence, U.S. Pat. No. 5,005,813, FIG. 6). Other types of mounting apparatus include screw mountings applied in radial directions (see Bricker, U.S. Pat. No. 4,583,432, FIG. 6) and split V-blocks (see George, U.S. Pat. No. 4,445,678). These systems are either too unstable for some applications or are not adaptable to the various sizes and shapes of cross-sectional work pieces such as rectangular tubing.
When the end of a circular cross-section tubing is cut in a particular shape so as to conform or mate with another tubing or surface, known as "coping," the tubing is rotated adjacent a cutting instrument while the tubing is simultaneously moved back and forth to achieve the desired cut (see FIG. 1). Coping is used in architectural applications, structural applications, and any other application where a lattice of tubing is connected at acute angles. There currently exists machines which clamp and rotate circular tubing so that they may be cut in this manner and, for this reason, circular tubing is often preferred to other shapes of tubing. These machines rely on the characteristic of circular tubing which automatically centers the tubing for rotation when the tubing is laterally constrained. That is to say, when the circular tubing is rotated on its axis, a stationary cutting tool can be used to create the desired shape and the tubing will not wobble when rotated due to the proper centering. This characteristic is exclusive to circular tubing, whereas other shaped tubing will not automatically be rotationally centered in a restraining device. Because of the difficulty of centering a noncircular cross-sectional tubing such as a rectangular tubing, this type of tubing is difficult to cope. Rectangular cross-section tubing offers an artistic alternative to circular tubing, but heretofore it had usually been eschewed because the coping of rectangular tubing had to be performed manually. Manual coping introduces errors and waste, and is labor intensive, driving up the cost of using rectangular tubing. The difficulties in automating the coping of rectangular tubing lie in accurately centering the tubing and rotating the tubing adjacent a cutting instrument which may be fixed or difficult to maneuver. For these reasons, the use of rectangular tubing and other noncircular tubing is discouraged in favor of circular tubing.
The prior art lacks a system for clamping and maneuvering rectangular tubing which can accurately and automatically center the tubing and permit rotation about an axis such as would allow the rectangular tubing to be coped in an automated manner. The ideal system would preferably operate on circular, square, rectangular, as well as other cross-sectional tubing to provide versatility from a single system.